Turf and ornamental grasses are subject to various pathogenic fungi which affect them under different temperature regimes (−20 to 45° C.) in all seasons and even under snow cover. Control of phytopathogenic fungi such as dollar spot (Sclerotinia homeocarpa), brown patch (Rhizoctonia solani), foliar and basal Anthracnose (Colletotrichum cereale) in warm- and cool-season grasses, or snow molds (Microdochium nivale, Typhula incarnata, and Typhula ishikariensis) in regions and climates with long duration snow cover is particularly important in high-value turfgrass used for golf courses and sod farms.
Different commercial fungicides are known and used for treating these turf diseases. Known treatments comprise repeated applications of fungicides in-season to prevent or for curative efficacy of incipient lesions, to prevent premature senescence, bleaching, or blade death, and to improve green-up and turf quality before or after snow cover where snow cover is historically longer than 60 days. Researchers and experienced turfgrass managers have long come to realize that repeated applications of the same fungicide, or fungicides of the same class inhibiting a specific metabolic site, or fungicides from different classes but possessing the same biochemical mode of action, can promote rapid onset of resistance by the pathogen or promote other pathogens released from their normal competition such that whole categories of fungicides can be lost as effective agents of disease control.
More recently, golf superintendants, lawn care specialists and managers of turfgrass have learned to treat high-value turf in a programmatic way in which fungicides with different biochemical modes of action are rotated throughout the season in an effort to manage resistance. This requires end-users to procure and inventory several different fungicides, each with their own specific concentration and regulatory instructions, and to study each label in order to comply with EPA-approved use rates that provide effective control but prevent turfgrass injury due to improper sequencing of applications or over-treatment due to conflicting demands on treatment intervals imposed by each fungicide. Some fungicides require short re-treatment intervals, such as contact fungicides, while other fungicides with limited or fully systemic properties permit longer intervals between re-treatment. As a result, program spraying is often complex given the variety of use rates, treatment intervals, and whether or not a given fungicide works solely as a preventative or can be used to treat turf with existing lesions or other symptoms of infection.
Another approach has been to combine fungicides, typically with different biochemical modes of action, in one concentrate in an effort to forestall resistance, broaden the spectrum of control, and to obviate the need to inventory the many individual brands of fungicides otherwise necessary. Combinations of chlorothalonil (a contact nitrile)+propiconazole (a sterol biosynthesis inhibitor) exist, as does a combination of thiophanate methyl (a systemic benzimidazole)+iprodione (a dicarboximide with acropetal penetration of grass blades). In the prior art only two and three way mixtures of fungicides for foliar application are presently known. For example, U.S. Pat. No. 5,240,952 discloses a synergistic composition of tebuconazole with iprodione; US Patent Application Publication No. US 2008/0269174 discloses a combination of tebuconazole with chlorothalonil; and U.S. Pat. No. 8,377,850 discloses a synergistic composition, comprising: trifloxystrobin, iprodione, and phthalocyanine green pigment Green 7.
Chlorothalonil was first described by N. J. Turner et al. (Contrib. Boyce Thompson Inst., 1964, 22, 303).
Iprodione was first described by L. Lacroix et al. (Phytiatr. Phytopharm., 1974, 23, 165).
Thiophanate methyl was first described by K. Ishii (Abstr. Int. Congr. Plant Prot., 7th, Paris, 1970, p. 200).
Tebuconazole was first described by Kuck & Berg (Mitt. Biol. Bundesanstalt. Land.-Forstwirtsch. Berlin-Dahlem, 1986, 232, 196).
While these two-way fungicide combinations improve the convenience of addressing various turfgrass diseases using multiple modes of action or target sites they have been shown to not provide a complete solution to in-season or snow mold disease management. The recommended use rates of these combinations often burden the environment in applying as much total fungicide as tank-mixes of each individual fungicide. These combinations of fungicides or tank-mixes show additive effects at best but not more. A three-way fungicide combination is also known but it contains an active ingredient (a sterol biosynthesis inhibitor) well known to phase into layers on the shelf and display plant growth regulator effects, which when used repeatedly or under periods of high temperatures often reduces playability of greens due to turf-thinning. Accordingly, there remains a need in the art to develop an effective mixture and composition thereof which affects all season fungi and treats a broad spectrum of fungal diseases economically while lowering the chemical burden on the environment.